Multiple-rate compressible liquid spring



Sept. l5, 1959 Y b/i /0/ G. L. WILLIAMS 2,904,328 MULTIPLE-RATE coMPREssIBLE LIQUID SPRING Filed oct. 26, 1955 I :I-i "-l' y A 5 V/ Z5 f 2i 25'/ 277 '4:

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Facf: /4511 United States Patent Ctiice MULTIPLE-RATE COMPRESSIBLE LIQUID SPRING Application October 26, 1955, Serial No. 542,917

'4 Claims. (Cl. 267-1) The present invention relates generally to springs and relates more particularly to multiple rate compressible liquid type springs for ruse in instances wherein large forces acting over short distances are encountered.

While compressible liquid type. springs have been known heretofore, the previously available arrangements have been limited in their application. These prevlous liquid'springs have had generally linear characteristics and were not adaptable to dilerent situations requrring nonlinear operating characteristics. For example, in rebound shock devices utilized for test purposes, it 1s deslrable that the force, or acceleration, applied by the spring have -a sharp rise followed by a relatively at plateau and relatively slow return vto zero. Mechanical. types of-springsand other shock absorbing devices are not able to produce the desired resultv nor are the linear liquid type springs suitable for the purpose.

It is accordinglyoue important Aobject of the present invention to providea multiple rate compressible liquid spring having strongly nonlinear operating characteristics.

Itis another important object of the present invention to provide a multiple rate compressible liquid type spring employing a plurality of chambers filled with a compressible liquid under pressure.

It is a further important object of the present invention to provide a multiple rate compressible liquid type spring arrangement including in combination therewith novel check valve means employed between at least two liquid lilled chambers thereof.

It isfstill another object of the present invention to provide a spring arrangement employing at least a pair of chambers divided by a movable wall, liquid contained within these chambers being maintained under pressure.

Other and further important objects of the present invention will become apparent from the disclosures in the following detailed specilication, appended claims and accompanying drawing, wherein:

Figurev l is a sectional view showing the multiple rate compressible liquid type spring of the present invention;

Fig. 2 is an enlarged fragmentary sectional View showing details of a check valve employed with a present spring arrangement; and

Fig. 3 is a diagram illustrating a typical operating schedule for the present liquid spring arrangement.

With reference to the drawing the compressible liquid type spring of the present invention includes a housing indicated generally at 10. The housing includes an upper or top portion 11, an intermediate portion 12 and a base or lower portion 13. The upper portion 11 has formed therein, a first chamber 14, while the intermediate portion 12 of the housing has an elongated bore 15 therethrough which defines a second chamber within the housing 10. The lower end of the chamber 15 is formed by an enlarged annular recess 16. The base portion 13 of the housing 10 has a recess 17 defining a third chamber, there being a transverse partition 18 disposed within a recess 20 in the upper end of the chamber 17, a spacer ring 21 being disposed between one side of the partition 18 and a shoulder 22 on one end of the recess 20. An upper surface of the partition 18 is adapted for engagement with a lower surface of the intermediate housing portion 12, there being an annular sealing ring 23 disposed in the portion 12 and adapted for engagement with the upper surface of the partition 18. A second annular sealing ring 24 is disposed in an annular groove in the upper housing portion 11 and adapted for cooperation with an upper surface of the intermediate housing portion 12. The various housing portions 11, 12 and 13, the partition 18 and spacer ring 21 are retained in position by means of a plurality of clamping studs 25 and nuts 26, the studs 25 being secured to the base portion 13, extending through the intermediate portion 12, with the nuts 26 being adapted and second chambers 14 and 15.

for engagement with an upper surface of the upper housing portion 11.

The chamber 15 has a piston 27 slidably disposed therein and defining a movable wall between the first The piston 27 has an extension portion 28 which is disposed through the chamber 14 and has an end adapted to limit the upward travel of the piston. An operating or output member is defined by a shaft 30 that is connected to the piston 27 and extends through a bore 31 formed axially within the` housing portion 11. A packing 32 is retained in position about a shaft 30 by means of a gland 33, which threadably engages the housing portion 11, in order to provide a liquid-tight seal about the shaft 30.

The partition 18, disposed between the second and third chambers 15 and of check valves indicated generally at 34. The check valves 34 are shown in detail in Fig. 2 and include valve retaining members 35 disposed tightly in bores `36 in the lower surface of the partition 18. Reduced diameter passageways 37 communicate between the upper ends of the bores 36 and the recess portion 16 of the cham ber 15. p The valve retaining members 35 are transversely slotted as at 38, there being disk type valve members 40 disposed in upwardly directed annular recesses 41 in the retaining members 35. The valve members 40 are adapted for cooperation with upper walls of the recesses 36 to occlude the passageways 37 and prevent uid flow from the third chamber 17 to the second chamfber 15, while still permitting free llow from the second chamber 15 to the third chamber 17. The existence of greater pressure in the chamber 17 and a differential across the partition 18 is adapted to maintain the valve disks in closed positions. For a purpose to be hereinafter more fully described, the partition 18 is further provided with an orifice bleed passageway 42 therethrough.

For purposes of the present invention and description thereof, it is assumed that the piston 27 forms a slidable liquid-tight iit within the bore dening the second charnber 15, in order that there may be very little if any fluid flow thereacross. It is further assumed that each of the first, second and third chambers 14, 15 and 17 are sealed and closed chambers except for the communication provided between the second and third chambers by way of the check values 34 and bleed orifice 42. Each of the chambers 14, 15 and 17 are lled with a compressible liquid such as, for example, a silicone material, with this material being installed in chambers 15 and 17 under a pressure in the order of 10,000 p.s.i., for example, and at a pressure of approximately 20,000 p.s.i. in chamber 14. Pressures across ythe piston 27 are in equilibrium with little or no force being transmitted to the upper wall of chamber 14 by the extension 28.

When downward compressive shock is applied to the Patented Sept. 15, 1959 17, has disposed therein a pairI shaft 30, the. piston 27 will be moved downwardly to compress the liquid inthe second and third chambers 15 and 17 by passage from/the chamber 15 through the check valves 34 and into the. chamber 17. Concurrently, theliquid. in the chamber. 1.4;Wil1 expandir@ the. upper. portion of the bare. 1.5. uarlffbbnressbrb. tbereadfna to. zero. whereaftsr anfevabuated Space Will be definedv inja portion of the chamber 14, with pressure inL the climber 1,4 thbreatrer being negligible, and: defined. au15' by` vapor characteristics of; the silicone material contained within; rhisrst Charrrbsr 14- It mayV thus be seen, with reference to the. diagram of Eig. 3Lhatappro1imately 700D. pounds of force, for err-. arnplg will: be required to displace. thel piston slightly more than .2. of an inch while` additional movement ofthev pistn for. approximately .8 ot anv inch will require forceoniy approximately an additional 5O0 V pounds, forY a total or 7500 :pounds. Thus, the line 43on' the graph will rlseto. the pointX as the piston 27. is being moved downwardly in thev bore 15, with the point X being reached when, the pressure of the silicone material in. the chamber `14 reaches zero. Thereafter, the plateau defined by the. line 44 is traversed until `a point Y is reached. The line 45 represents a return schedule for the shaft 30, and piston 27, with the check valves 34,z

servingtzo trap a quantity of the silicone materialv inthe chamber4 17 and to prevent rreverse ow to the chamber 115thuvs spacing the schedule defined by the line, 4,5..

from; the schedule defined by the line 43 andV preventing,

return by. way of the schedule deiined by the linesV 4,4

and 43, 4'Operation of. the present device through acorn plete cycle thereof tairesk place within a very short period df' time. Say for example.. 2.0. to. 30 millisecarldswiflr the silicone material under` pressure in the chamber 17 being' thereafter bled to the chamber 1-5, by way of the orceV in the Partition 1,18., whereby t0 equalize preparaban. each. side of the partition 18 and prepare the device Vfor a aextsyclef As shown in Fig. 1, the spacer ring 21, on one side of the partitionv 1 8,` may be removed, and the ring .21 being placedfabove the partition 18, whereby electirvely to change the volumes ,ofi the second and third chambers 175 and 17 respectively in'order that diiferent schedulesA may-be followed as may specific requirements.

Having thus described the invention and the present embodimentl thereof, it is desired to emphasize the fact that many modiiications may be resorted to in a manner be necessary for particular limited only by a illSi interpretation of the following claims.

What is claimed is:

l. A multiple rate compressible liquidV spring device comprising, in combination: a composite housing; rst, secondfand third chambers in said housing;'a piston def ning a movable wall between said rst and second chambers; an output shaft connected to said piston; and extending outwardly from saidhousing; uid s ealing4 means about said shaft; a partition disposed between saidy second and third chambers; check valve means carried by said partition, free fluid ilowl across said check valve means being in a direction from said second chamber to said third chamber; orifice means between said secondA and third chambers; and a compressible liquid in each of said chambers, said liquid in said iii-st4 chamber normally at a pressure greater than a pressure of said liquid in said second and third chambers.

2. A multiple rate compressible liquid spring device comprising, in combination: a composite housing; first, second and third chambers in said housing; a lpiston defining a movable wall between said iirst and second chambers; an output shaft connected to said piston and extending outwardly from said housing; uid sealing means about said shaft;'an adjustable partition disposed between said second and third chambers; check 'valve means carried. by said' partition, freeA fluid ow across said check valve means vbeing in a direction from said second chamberto said third chamber; orifice meanslbcj, tween saidy second and third chambers; and a compressible liquid under pressure in each of said chambers, said liquid in said iirst chamberY normally being at a pressureI greater than a pressure of said liquid in said second and third chambers.

3. A multiple rate compressible liquid spring device comprising, in combination: a composite housing; rst, second, and third chambers., in` saidY hoixsing;i a piston, deains a gravable Wall betvinfSaidirSt aad. Seanad chambers, an .output shaftv Connected to. said piston.` arid'. extendingI outwardly, from, s'aidhousing; 'iluid `sealing @sans ,21,1911? Sai@ Shafl. afRartitQn. dinosbdbetwen' Said, Segond and third. chambers; check 'valve mesas.. Carfied@ br Said. Partition, free. uidaw acrossx Said Cheek. valve-means, bfeias in a direction from. said second. Cham: be:` to said,A rhirdfchamberr Orifigelmsaas. between Said second and,v third. chambers,4 said `third .chamber having;

a. volume. greater than, ai comb/ed. volume of Sairlrst and Secondv hambersi and of, said, chambers, said liqiiidnsaii.A iirst chamber norwally beiasara pressure greater than, a Pressure .0f 'Said t chambers; an. output Shaft. Connected .i0 Said. Piston: and" extending outwardlyfrongi said4 housing; fluid scaling means. about Said shaft; .au adiustablepa'rtition disposedl between said second and third` chambers; freefilo'atingj disc, c hecl valve means carried by said parti tion, freev fluid. fiow across said -check valve meansgbeing in' a direction' from, said, second chamber,A to said third 'chain-l ber; orifice means between. said seondandthirdjchamf bers, said third chamber, having a'vvolumegreater than, a combinedvomme of sadrst and4 second chambers; anda compressible liquidunderpressureieach of said1 chambers?. Said; lisiaid in. said'rst chamber.. narlmally brins: at aV pressure greater. rtha'na pressure. of said liqirid. insaid-second'and third,chambers.

Reiereucesiredintbe lrv Ofrfhis: Patent UNITED STATES` BATENTS.

a, o9 rnpressib'lel liquid in'y each' 

